function s1_generate_a_series_of_files(){
 for i in {1..100};
do
echo $i> /tmp/new_file$i;
done
}

function s2_list_4_files_in_long_format_about_accout_and_group(){
 ls -l /etc/{passwd,shadow,group,gshadow} |sort -d
}

function s3_find_items_related_to_given_username(){
  grep -h $1 /etc/{passwd,shadow} |sort -d
}

function s4_find_items_related_to_given_name(){
 grep -h $1 /etc/{group,gshadow} |sort -d
}
function s5_create_group_for_given_group_names(){
 groupadd rnd && groupadd itoperation
}
function s6_create_users_and_set_their_group_as_required(){
 useradd -G rnd adam 
 useradd -G rnd bob 
 useradd -G rnd edward
 useradd -G itoperation calvin 
 useradd -G itoperation david 
}

function s7_change_users_shell(){
 usermod -s /usr/bin/sh adam && usermod -s /usr/bin/sh edward
}

function s8_set_password_change_policy(){
passwd -n 10 -x 60 -w 10 adam
passwd -n 10 -x 60 -w 10 bob
passwd -n 10 -x 60 -w 10 david
passwd -n 10 -x 60 -w 10 calvin
passwd -n 10 -x 60 -w 10 edward
}

function s9_set_passwor_for_five_users(){
 usernames=(adam bob calvin david edward)
 passwards=("$1" "$2" "$3" "$4" "$5")
for i in $(seq 0 4);do
echo "${usernames[$i]}:${passwords[$i]}" |sudo chpasswd
done
}

function s10_lock_bobs_password(){
 usermod -L bob
}

function s11_include_adam_into_wheel_group(){
 usermod -aG wheel adam
}

function s12_change_files_permission(){
for i in {1..100};do
filename="/tmp/new_file${i}" > $filename
if(($i %3 == 0));
then
sudo chmod 640 /tmp/$filename
 fi
done
}
